Flexible shaft coupling



Se t. 6 192 N416@ v p 7 a. FAST i FLEXIBLE SHAFT COUPLING Fild March 17. 1925 2 sheets-sheet l Eiga; 6

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Sept. 6, -G. FAST v 'FLEXIBLE SHAFT COUPLING Filed March 17, 1925 f 2 Sheets-Sheet 2 Ihr/senior? Guai@ Lge Ew si,

Patented Sept. 6, 1927.

UNITED GUSTAVE FAST, OF ANNAPOLIS, MARYLAND, ASSIGNOR vT THE BARTLETT HAYWARD COMPANY, 0F BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND.

FLEXIBLE SHAFT COUPLING.

Application flied March 17, 1925. serial' N. 16,190.

i. The inventicn is an improvement upon that type of flexible shaft coupling disclosed by me in Letters Patent of the Unlted States Reissue No. 15,177 dated August 16, 1921, 6 and concerns the rocking bearing between the sleeve and the shaft ends, and other features as will be described hereinafter and particularly pointed out in the claims.

In the accompanying drawings 10 Figure 1 is a part side elevation and a part longitudinal sectional view of a'shaft coupling embodying the invention.

Fig. 2 is a similar view of one half of a coupling showing a spherical bearing of another form.

Fig. 3 is a similar view of a portion of a coupling with amodified form of bearing. 0 Figs. 4 and 5 show other forms of bearings.

Fig. 6 is a developed view of one set ofthe intermeshing teeth of the coupling. Referring to Fig. 1 the coupling includes the shaft hubs 1, 1 to be keyedto the shaft ends, and the sleeve 3 with intermeshing rows of teeth at 2.

The sleeve has end rings,flanges or plates` these rings are curved to conform to a sec-l tion of a sphere whose'center is at the axis of the coupling at the point C which is in a plane extendingtransversely to and intermediate the len h of the intermeshing teeth 2. Upon' this spherical surface of the ring the inner peripheral face of the flange 4a bears and rocks, when the shafts are misw aligned. The inner peripheral bearingface of the flange 4 in this form is shaped to conform to the spherical 4face of the ring 6.

Instead of making the flange 4a with the spherical inner face, this face may be made cylindrical as in Fig. 2 and a ring 6a may be employed having an outer peripheral face and a concave inner peripheral face curved to conform to the sphere above mentioned and bearing on the outer similarly shaped face of the ring 6. In this formthe ring 6 is held in lace by a .collar 6b which is screw threadetl onto theV shaft Kvariations in the diameter of the spherical cylindrical v hub. Instead of employing a separate ring having the spherical bearing face, a spherical bearing-may be employed integral with the shaft hub as in Fig. 3 at 6c.

In all the lforms above described the spherical bearing is within the circle in which the intermeshing teeth 2 lie and in all said 60 forms the flan e 4 may be split at intervals as shown at 4c 1n Fig. 3 the purpose of which is'to make ethis flange resilient to the small degree desirable in order to compensate for bearing whether this be of one form o r the other of those described above.

It will be understood that the shaft hubs are mounted with a press fit upon the shaft ends and the de ee of this press fit varies according to di erent standards established by different users, -thus rendering it impossible, in quantit production, to adopt a standard that will exactly meet all conditions because different degrees of press fit result in slight variations in the diameters of the shaft hubs and their 'spherical bearing parts or members, and it is to accommodate these slight Variations from the prescribed diameter of the bearing that the flange 4a is made slightly yielding. This split ring or flange is made of such diameter that it can be forced into itsproper relation to the hub bearing with slight pressure. Without this split flange the fitting of-the bearin between' the sleeve of the coupling an the shaft hub would be more difficult to perform in view of the high degree of accuracy necessary, and the different diameters which would be encountered. If the clearance at the bearingis too great the sleeve will vibrate and be noisy and on the other hand, if it is too tight, the lateral flexibility of the coupling or its capacity to permlt slightendwise relative movement of the shaft ends will be impaired. The splitange will ob viate these objections.

Instead of having the spherical bearing within the circle of teeth it may be located outside thereof as in Figs. 4 and 5. In the form shown in Fig. 4 the teeth 2' of the shaft hubs are located on .the linterior of the i is formed on the outer peripheral face of the Harige 8 at 9 andthe bearing surface on the sleeve is provided at 10 on the end section 11 of the sleeve casing.l rl`his surface is cylindrical. The sleeve end section 11 or fiange` is bolted to the sect-ion 12 of the sleeve andthe two sections 12 areconnected together by a central section 13.. Bolts 14 serve to fasten the sections together.

Fig. 5 is similar to Fig. 4 excepting that arng 15 having its inner peripheral face spherical and its outer peripheralvface cylin drical is interposed between the spherical bearing face of the hub flange 8 and the end section 11 of the sleeve. ,.f

-In all cases above described there is provided a spherical bearing. the center of which is at the axis of the coupling and in a. plane transverse ,to and intermediate the lengt-h of the internieshing teeth so thatthe` sleeve and shaft hut will not assume an ec centric relation when the shafts are misaligned, as would be the case if the center about which the sleeve and shaft hub rocks 1 relative to each other were located to one slde ot' the plane mentioned.

These various forms of spherical bearings.l

ofteeth may be formed with their side or` bearing faces com-'exly curved from end to end` and these may mesh with straight teeth of the companion row or the latter row may be curved also. The object of this form of tooth is to bring more teeth into intimate relation for imparting theA drive from one to the other when the shafts are considerably misaligned and the shock loads are excessive, such for instance. as in rolling mill service. Teeth atI 180 apart are in engagement. at

the points marked Contact, with the adjacent teeth. which are represented as being straight teeth. It will be noted that while -the next tooth marked m is not in actua1 contact wit-h its adjacent tooth y there is only a minute space separating them and this close proximity of these teeth is not'merely at one. point but exists for a considerable length of the opposing faces of the teeth ai and g/ so that under heavy load these teeth will come into-driving contact for a material part of their length. and this will be true of other teeth along the row, due to the convex shape. of the sides of teeth The theoretically correct shape of tooth or load carrying surface which wuld main` tain contact on each and every tooth when considerably misaligned would be a spherical tooth. With such a tooth, however, on y account of its great curvature the area of proximity for a greater distance from the point of contact or the point of near contact than would be the case with spherical teeth and the oil film between the teeth, having a. definite thickness tends to distribute the pressure over a greater surface.v Y

With a sli htly curved tooth, the curve of which must bev a compromise between a straight and spherical or circular tooth. it is possible to bring a greater number of teeth into closer proximity without sacrificing too much contact surface along the tooth.

e The object is to lower the stress in the individual teeth during a shock `load period which may be many times'that of the normal ff load and at the same time have ample pressure distribution by the oil film which prevents wear.

As intimated "above, with the teeth of the oil film between the teeth plays an important part in assisting in transmitting the power from tooth to tooth and through a greater convexly curved side or bearing'faces the area of the opposed faces' of thedteeth than Y I would be thecase with either spherical' teeth or straight teeth.

The lubricant is supplied to the sleeve through a filling port 17, Fig. 1, and the amount of lubricant which the/sleeve contains should be sufficient to submerge the teeth and also thespherical bearing surfaces ,when the coupling is at rest.. The lubricant will be caused to pass between the. teeth by centrifugal force. The sleeve is provided with lips or lflanges 18 and oil ports 19, the said anges are so located that the lubricant will be mamtamed at the proper depth withi in the sleeve. y

It is important in a shaft coupling of the type described had upon an oil film betweenthe teeth to carry the load. without metallic contact., that the oil`be retained in the sleeve or casing. When the coupling is in service under load it floats or moves axially due to shocks 'from the coupled shafts. These shocks will be imparted to or taken by thel end plates or flanges of the sleeve, with the result, if these end plates are held by screws, that these fasteningswill crystallize and ing a leak at. these points. I, therefore, provide such a construction of the sleeve .with its end plates or flanges that no leak can occur at the points where the main body y,of the sleeve is joined to the end plates.

In order to insure against leakage of oil I hermetically seifl the end plates or rings break. thus causabove, in which reliance is assises' 4 at 21 to lthe main body of the sleevlas in Fig. 2 or 'by means'of lspinninga fian'ged joint between these two members as at .20, Fig. 3, or by first forming the joint by splnning and then welding it.

In coupling the two shafts it is sometimes found necessary to meet a condition where .a fine angular adjustment of one shaft in relation to the other is necessary, such for instance as in coupling the shafts of two alternators and at the 'same time synchronizing them as to phase. For this purpose I provide a different number ofteeth in the set at one end of the coupling from the number in the set at `the other end of the coupling, say that one set has 6() teeth and the set at the opposite end of the coupling has 61 teeth. This will provide for a fine angular adjustment of one shaft in relation to the other, say approximately equal to 0.10 because:

' and the hermetic sealing of the sleeve so that in all cases where the feature. may be transposed from figure to figure, thel 1/60 X 1/61 1/3660 of one revolution, or

360o/3660 0.1 approximately It will be noted that features shown in one figure 'ofthe drawing may be embodied in the other figures such for instance as the different numbers of teeth, the split fiange ends of the description is to be re arded as applying as through shownin a single form of the invent-ion.

The sleeve is formed of transverse sections and by reason of this constructionone result is that 4the separate bearing ring can be i m assembled in relation to the sleeve. In Fig.

1 the sectional featureconsists of the two members like 3 bolted together. The rings -6 are assembled within the vsections before they are bolted together. This permits the use of the flange 18 of sufficient height to hold oil up to the proper line.

' In Fig. 5l the sectional feature is carried out for assembly by making the fiange or end portion 11 of the sleeve separate from the rest thereof. y n' v In Fig. 4 also'the sectional feature of the sleeve comprises the separate end section `11.

1. A flexible shaft coupling com rising a sleeve having at its end a row 'o the bearing surface of which conforms to l the section of a sphere whose center lis at the teeth, a. shafthub having a row of teeth meshing 'axis of the coupling in av plane transverse'. to and intermediate the length of the inter' meshing teeth, and a surface on the-other,l

part of like spherical formation with which,l

the spherical surface of the vfiange contacts, said* flange being split transversely, substantially as described. f

2. A flexible coupling for shafts compris.v

ing a sleeve having at its end a rowof teeth, a shaft hub having` a row of teeth meshing with the teeth on the lsleeve and an annular bearing between the sleeve and shaft hub comprising an annular fiange on one part, having a bearing surface on the other part, said annular flange being split at intervals rendering it fiexible to .accommodate itself to variations of the bearing from a -prescribed diameter, substantially as described.

3. A flexible coupling for shafts comprising a sleeve having.v at its end a row of teeth, a shaft hub having a row of with the teeth on the sleeve and an annular -bearingbetween thesleeve and shaft hub comprising an annular fiange projecting inwardly from the end wall of the sleevev into an annual recess inthe shaft hub, and engagteeth meshing ing said hub, said flange being split at inter-v vals to'4 provide resilience in said flange,

substantially as described.

4. A-fiexible shaft coupling comprising .a member having al row of teeth row of teeth on .another member, and having rocking movementrelative thereto under misalignment of the shafts, the teeth of the to engage a said first menmember having'a. row of teeth the side faces 'p of which are curved convexly lengthwise of the coupling, anda member having a row of teeth with straight sidesextending length wise of the coupling, said straight sided teeth being elongated -in respect to the teeth first mentioned, and meshing therewith whereby bearing contact between the teeth is maintained under' misalignment of the shafts, substantially as described. v v6. A fiexible shaft Couplin comprising a sleeve having a row of teet at leach end, shaft hubs having teeth engaging the teeth of the sleeve, said sleeve having an end wall, the body of the sleevel being spun into connection withsaid end wall to prevent escape of oil, substantiallyas described.

In testimony whereof I affix my signature.

` GUSTAVE FAST. 

